Isosurfacing_3/marching_cubes.cpp

#include <CGAL/Simple_cartesian.h>
 
#include <CGAL/Isosurfacing_3/Cartesian_grid_3.h>
#include <CGAL/Isosurfacing_3/Value_function_3.h>
#include <CGAL/Isosurfacing_3/marching_cubes_3.h>
#include <CGAL/Isosurfacing_3/Marching_cubes_domain_3.h>
 
#include <CGAL/IO/polygon_soup_io.h>
 
#include <vector>
 
using Kernel = CGAL::Simple_cartesian<double>;
using FT = typename Kernel::FT;
using Point = typename Kernel::Point_3;
using Vector = typename Kernel::Vector_3;
 
using Grid = CGAL::Isosurfacing::Cartesian_grid_3<Kernel>;
using Values = CGAL::Isosurfacing::Value_function_3<Grid>;
using Domain = CGAL::Isosurfacing::Marching_cubes_domain_3<Grid, Values>;
 
using Point_range = std::vector<Point>;
using Polygon_range = std::vector<std::vector<std::size_t> >;
 
int main(int argc, char** argv)
{
  const FT isovalue = (argc > 1) ? std::stod(argv[1]) : 0.8;
 
  // create bounding box and grid
  const CGAL::Bbox_3 bbox { -1., -1., -1., 1., 1., 1. };
  Grid grid { bbox, CGAL::make_array<std::size_t>(30, 30, 30) };
 
  std::cout << "Span: " << grid.span() << std::endl;
  std::cout << "Cell dimensions: " << grid.spacing()[0] << " " << grid.spacing()[1] << " " << grid.spacing()[2] << std::endl;
  std::cout << "Cell #: " << grid.xdim() << ", " << grid.ydim() << ", " << grid.zdim() << std::endl;
 
  // fill up values
  auto sphere_value_fn = [](const Point& p) -> FT
  {
    return sqrt(p.x()*p.x() + p.y()*p.y() + p.z()*p.z());
  };
 
  Values values { sphere_value_fn, grid };
 
  // Below is equivalent to:
  //   Domain domain { grid, values };
  Domain domain = CGAL::Isosurfacing::create_marching_cubes_domain_3(grid, values);
 
  Point_range points;
  Polygon_range triangles;
 
  // run marching cubes isosurfacing
  std::cout << "Running Marching Cubes with isovalue = " << isovalue << std::endl;
  CGAL::Isosurfacing::marching_cubes<CGAL::Parallel_if_available_tag>(domain, isovalue, points, triangles,
                                                                      CGAL::parameters::use_topologically_correct_marching_cubes(true));
 
  std::cout << "Output #vertices: " << points.size() << std::endl;
  std::cout << "Output #triangles: " << triangles.size() << std::endl;
  CGAL::IO::write_polygon_soup("marching_cubes.off", points, triangles);
 
  std::cout << "Done" << std::endl;
 
  return EXIT_SUCCESS;
}